81934649 has 2 divisors, whose sum is σ = 81934650. Its totient is φ = 81934648.

The previous prime is 81934637. The next prime is 81934663. The reversal of 81934649 is 94643918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 67947049 + 13987600 = 8243^2 + 3740^2 .

It is a cyclic number.

It is not a de Polignac number, because 81934649 - 2¹² = 81930553 is a prime.

It is not a weakly prime, because it can be changed into another prime (81934609) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40967324 + 40967325.

It is an arithmetic number, because the mean of its divisors is an integer number (40967325).

Almost surely, 2^81934649 is an apocalyptic number.

It is an amenable number.

81934649 is a deficient number, since it is larger than the sum of its proper divisors (1).

81934649 is an equidigital number, since it uses as much as digits as its factorization.

81934649 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 186624, while the sum is 44.

The square root of 81934649 is about 9051.7760135788. The cubic root of 81934649 is about 434.3327048100.

The spelling of 81934649 in words is "eighty-one million, nine hundred thirty-four thousand, six hundred forty-nine".